OK, this is really bizarre. I can force on the apps that are marked as "On Demand" but I cannot install any of the mandatory automatic install apps.
Notice iPlayer, Photoshop, and Prime Video. All I installed from the Jamf School console.

Make sure the licenses are assigned for managed deployment, and that you actually have licenses in ASM/ABM for that app and the MDM in question.
If the licenses are assigned correctly check for network blocks as you have already renewed the VPP certificate.
Make sure the licenses are assigned for managed deployment, and that you actually have licenses in ASM/ABM for that app and the MDM in question.
If the licenses are assigned correctly check for network blocks as you have already renewed the VPP certificate.
I have assignable licenses. Just tried setting up another iPad for a different user and everything worked as it should.
This iPad, I tried blanking it and then enrolling it as me (rather than the teacher) but the apps still sit on Waiting for Licenses.
I'm going to try trashing the device and then putting it back. It seems that Jamf is stuck with this device only. Will report back.
OK, fixed it.
I had to remove the teacher from the group that gets the apps automatically installed, this cleared the pending apps list. Then I put them back in to the correct group and all the apps started to install. What a pain.